Because modern communication is increasingly ad hoc and mobile, there is a need for authentication of mobile devices. In wireless networks where security, resource control, and/or accounting is managed, a mobile device may need to be authenticated and authorized before the mobile device is granted access to services in the wireless network. Further, secure communications are necessary in wireless networks because the communication link in which communications take place is easily observable and easily tampered with. For example, a false message may be inserted into a communication between a mobile device and the wireless network to which the mobile device is connected. Such secure communications necessarily require authentication of the mobile device.
There are many existing authentication techniques, however, the existing techniques are lacking for a number of reasons. The first category of authentication techniques involves the use of public key cryptography. Examples of public key cryptography include Digital Signature Standard (DSS), Rivest Shamir Adelman (RSA), and Diffie-Hellman algorithms. However, such examples are computationally intensive which makes them inappropriate as a general technique for a wireless network environment where mobile devices are limited in computational and power capabilities. Such public key techniques may be used on initial connection, when more delay can be tolerated, but may not be acceptable as part of the process to authenticate to a new connection point during a real-time transfer such as a voice conversation.
The second category of authentication techniques requires the release by a home network to a remote network of a secret also known to the mobile device. These techniques are also lacking because such techniques reduce security and control. For example, releasing the secret to a remote network may allow a malign remote network to impersonate the home network and perform improper authentications. Further, giving the secret to a remote network may allow the remote network to eavesdrop on the mobile device's communications with subsequent remote networks which decreases the level of security in the wireless network.
The third category of authentication techniques involves a large number of sequential protocol exchanges (round trips) between the mobile device, remote network, and the home network which induces much latency. Examples of such techniques involve the flow of messages 1) from the mobile device through the remote network back to the home network and 2) from the home network back through the remote network to the mobile device. In certain applications where latency can be a critical problem, such as voice and other isochronous communications, having such latency is not acceptable. For example, a communication session between public safety personnel can not tolerate the significant delay or interruption to voice that such techniques cause.
Accordingly, there exists a need for an improved method of authenticating mobile devices.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.